Use of stereotactic body radiation therapy for oligometastatic recurrent prostate cancer: A systematic review

The purpose of this study is to evaluate the effectiveness and safety of stereotactic body radiation therapy (SBRT) in the management of oligometastatic recurrent prostate cancer (PCa) by means of a systematic review. Six databases were searched (CENTRAL, Embase, LILACS, PubMed, Scopus and Web of Science). Additionally, hand-searching and grey literature search were performed. The main outcomes were progression-free survival (PFS) and toxicity rates. Androgen deprivation therapy-free survival (ADT-FS), local control, pattern of recurrence, cancer-specific survival and overall survival were also assessed. Risk of bias and quality of evidence were judged with the aid of specific tools. Fourteen studies were included, involving 661 patients and 899 lesions (561 nodal, 336 bone, 2 liver). Median PFS and ADT-FS were around 1 to 3 years. Local control rates varied from 82 to 100% among researches with low risk of bias. Acute and late grade 2 toxicity was observed in 2.4% and 1.1% of the patients, respectively. One case of acute and two cases of late grade 3 toxicity were registered. Only one randomized study addresses this topic. Although it does not meet all the eligibility criteria, it is useful for the discussion. A quantitative analysis was not possible, nor were subgroup analyses, due to the significant heterogeneity of the interventions and outcomes reported. Longer follow-up period is required. SBRT seems to be a safe approach to metastatic lesions that might provide disease control and defer androgen deprivation therapy (ADT). Local control is better when higher radiation doses are employed.